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So that's about it randomly while driving (or with the engine off and the lights on) the headlights will just go dim. I haven't noticed the high beams doing it and it wouldn't be that big of a deal but it's so low it's very noticeable I go from great visibility to not being able to see someone stand 2 feet in front of the vehicle.

There's a sensor that performs a test and if its driven too soon after startup your voltmeter will drop when the headlights dim for a second. Dealer provided me with a TSB on this and I let it run for a minimum of 20-27secs when starting up(there's a noticeable tick/click when this happens) voltmeter may jump too. Scary yes, check the charging system. I hated it and thought it mat appear as if i was flashing my lights. Run it for 30seconds every startup. hasnt happened again in years. Occasionally I notice the voltmeter drop and jump back just as quick. headlights dimming after shutdown is the battery. No other way to keep em on otherwise

When they go dim is there a loss of power? Do the interior lights dim as well? Is the charging system gauge holding steady the whole time they go dim and back to normal?

Thanks for the help, it seems like a loss of power yes but no other power systems in the TB go dim (head lamps, gauge leds, etc.) the charge gauge is indeed holding steady the entire time (just verified). I've had the brights on plenty without that issue but the low beams it happens every time (both sides btw)

They were different for mine (the #'s) reseated, switched around and it stays ok then about 5 mins into turning it on it does the same thing, also note I've secured all connections I could find, disconnected the - terminal for 5 mins and reconnected, and reset the computer (by overturning the key for 30 secs).

So that's about it randomly while driving (or with the engine off and the lights on) the headlights will just go dim. I haven't noticed the high beams doing it and it wouldn't be that big of a deal but it's so low it's very noticeable I go from great visibility to not being able to see someone stand 2 feet in front of the vehicle.

Any advice or previous experience with this?

JaTech,

I am sorry you are experiencing this issue with your vehicle. I have researched your vehicle and there are currently no known issues as you have described. I recommend consulting with a certified technician, as I suspect an electrical issue. The technician will be able to offer more information after inspecting the vehicle.

If you need assistance locating a technician near you, please PM me your zip code for a listing.

I am sorry you are experiencing this issue with your vehicle. I have researched your vehicle and there are currently no known issues as you have described. I recommend consulting with a certified technician, as I suspect an electrical issue. The technician will be able to offer more information after inspecting the vehicle.

If you need assistance locating a technician near you, please PM me your zip code for a listing.

Louis (assisting Evan)
GM Customer Service

Looks like owners with this type of problems starting to come out and across the trailblazer forums, a lot of owners have been reporting this and this just happened to me and still no lowbeams after a week or so of troubleshooting it. THIS IS A KNOWN ISSUE now.

I replaced the 45 and 46 relays, #3 and #6, the 15a behind it (53), and the other ones too and no success. Checked the power and I am getting it so don't know what to do. I try to avoid the dealers as much as possible and I might just head over to an indy shop but I guess its a design flaw or something

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